Luminescent glass article and method of manufacturing the same

ABSTRACT

A luminescent glass article of the present invention includes a luminescent substance dispersed uniformly in glass, in which: light transmittance is 20 to 90% at a thickness of 10 mm; and an initial luminescence intensity just after irradiation of light of 1,000 lux for 20 min is 200 to 4,000 mcd/m 2 .

TECHNICAL FIELD

The present invention relates to a luminescent glass article mainly usedas pavements, building covering materials, building interior materials,art objects, guide lights, sidewalk lights, or foot lights, and to amethod of manufacturing the same.

BACKGROUND ART

Recently, numerous glass articles have been used as building materialswith diversification of building design. In particular, cases employingbuilding glass articles having improved functionality or decorativeproperties (design properties) using to light have increased lately.

However, pavements, building covering materials, building interiormaterials, art objects, guide lights in dark places requiring no highintensity illumination, illumination for lighting the sides of asidewalk, foot lights provided for recognition the presence of a wall orsteps, and the like which require a light source, such as an electricbulb or a fluorescent lamp, have limited design flexibility, and requiremaintenance. A building material, a so-called luminescent glass article,capable of absorbing ultraviolet light or visible light in sunlight orthe like replaces the above-described light sources by dischargingenergy thereof as light emissions for a long period of time. Theluminescent glass article requires no maintenance, can enhance designflexibility, and uses no electric power. Thus this glass article hasattracted attention from the viewpoint of energy-savings.

There is proposed a luminescent glass article in which glass having aspecific composition is capable of absorbing ultraviolet light orvisible light for light emission (see Patent Document 1, for example).

Further, there is proposed a luminescent glass article prepared bymixing glass powder particles with a luminescent substance and sinteringthe mixture (see Patent Document 2, for example).

[Patent Document 1] JP-A-2000-63145

[Patent Document 2] JP-A-11-293238

Meanwhile, the glass article disclosed in Patent Document 1, in whichthe glass itself exhibits luminescence, emits its own light. Foremission of light of various colors, glass having a composition for eachcolor must be manufactured, and the manufacture of glass articles havingdifferent luminescent colors has high costs.

The luminescent glass article described in Patent Document 2 contains asmuch as 20 wt % of an expensive luminescent substance, to therebyincrease cost and degrade mechanical strength due to poor sinteringproperty.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide: a luminescent glassarticle which has high mechanical strength, which provides sufficientluminescence intensity, and which can be manufactured at a low cost; anda method of manufacturing the same.

The inventors of the present invention have conducted intensive studies,and have found that the above object can be attained by: incorporatingan appropriate amount of a luminescent substance in glass to providelight transmission and allowing light emission of a luminescentsubstance present not only in a surface layer but also inside the glassarticle. Thus, the inventors have proposed the present invention.

A luminescent glass article of the present invention is achieved byincluding a luminescent substance dispersed uniformly in glass, inwhich: a light transmittance is 20 to 90% at a thickness of 10 mm, andthe initial luminescence intensity just after irradiation of light of1,000 lux for 20 min is 200 to 4,000 mcd/m².

Further, a luminescent glass article of the present invention ischaracterized by including a luminescent substance dispersed uniformlyin glass, in which a content of the luminescent substance is 0.1 to 5mass %.

A method of manufacturing a luminescent glass article of the presentinvention is achieved by: mixing a plurality of glass particles and aluminescent substance; filling the mixture into a refractory vessel; andsubjecting the mixture to heat treatment for sintering.

The luminescent glass article of the present invention has a lighttransmittance of 20% to 90% at a thickness of 10 mm, and has sufficientlight transmission. Thus, light reaches into the luminescent glassarticle, and the luminescent substance present thereinside can emitlight, which reaches the surface of the luminescent glass article. Theinitial luminescence intensity just after irradiation of light of 1,000lux for 20 min is 200 to 4,000 mcd/m². The light transmittance refers toa value obtained by: cutting the luminescent glass article into a sampleof 50×50×10 mm; subjecting both surfaces of the cut-out piece to opticalpolishing to prepare a plate sample; adjusting light directlyilluminated from a light source of a fluorescent lamp to an illuminancemeter at an illuminance of 1,000 lux; measuring an illuminance (lux) 10times with the sample placed between the fluorescent lamp and theilluminance meter; and dividing the average value thereof by 1,000 luxand multiplying the quotient by 100.

The light transmittance is in a range of preferably 30 to 80%, and morepreferably 40 to 65%.

The initial luminescence intensity is preferably in a range of 250 to2,500 mcd/m², and preferably in the 300 to 1,500 mcd/m².

The luminescent glass article of the present invention includes aluminescent substance dispersed uniformly in glass and a content of theluminescent substance that is 0.1 to 5 wt %. Thus, the luminescent glassarticle of the present invention has high mechanical strength, canprovide sufficient luminescence intensity, and can be manufactured atlow cost.

That is the luminescent glass article of the present invention that hasa content of the luminescent substance of 0.1 to 5 wt %. The luminescentsubstance does not inhibit sintering of the glass. Thus, the luminescentglass article has high mechanical strength, and thus can be formed intoa plate or block. A small content of the luminescent substance meansluminescent glass article can be manufactured at a low cost.

Luminescent substances of different luminescent colors may be used, orglass may contain colorants uniformly. Thus, the luminescent glassarticle can emit light of a desired color, and luminescent glassarticles having different luminescent colors can be manufactured at alow cost.

BEST MODE FOR CARRYING OUT THE INVENTION

A luminescent glass article of the present invention preferably has aluminescent substance content of 0.1 to 5 wt %. If the content of theluminescent substance is less than 0.1 wt %, sufficient luminescenceintensity cannot be obtained. If the content of the luminescentsubstance is more than 5 wt %, fluidity of glass degrades and fusionbonding of the glass is inhibited. Sufficient mechanical strength cannotbe obtained, and sufficient light transmission cannot be obtained. Thus,luminescence intensity is hardly improved, even with further addition ofthe luminescent substance. The luminescent substance is expensive, andthus further addition is not preferable cost-wise. The preferablecontent range of the luminescent substance is 0.3 to 4 mass %,preferably 0.5 to 2.9 mass %, and even better is 1.1 to 2.8 mass %.

The luminescent glass article of the present invention preferably hasthe softening point of glass, which is its base material, 1,100° C. orlower. If a glass softening point is higher than 1,100° C., glassforming requires a temperature higher than 1,200° C. Under suchtemperature conditions, the forming vessel for the glass article isliable to soften and deform and the glass article is difficult to form.Further, a luminescent material degrades, and luminescence is liable todegrade. The glass softening point is in a range of preferably 1,000° C.or lower, and more preferably 900° C. or lower.

Further, the luminescent glass article of the present inventionpreferably has a glass softening point of 650° C. or higher for highmechanical strength and high hardness. That is, a glass softening pointof 650° C. or higher provides strong interatomic bonding and highmechanical strength. The luminescent glass article is hard to break, hashigh hardness, and is hard to damage on the surface. The glass softeningpoint is preferably 700° C. or higher.

The luminescent glass article of the present invention is preferablycomposed soda-lime glass, borosilicate glass, aluminosilicate glass, oraluminoborosilicate glass to have sufficient chemical resistance andmechanical strength. To be specific, the soda-lime glass is preferably aglass containing 65 to 75% SiO₂, 0.5 to 3% Al₂O₃, 0 to 7% B₂O₃, 1 to 4%MgO, 5 to 10% CaO, 12 to 15% Na₂O, and 0 to 3% K₂O in mass %. Theborosilicate glass is preferably a glass containing 65 to 75% SiO₂, 3 to7% Al₂O₃, 10 to 15% B₂O₃, 0 to 3% CaO, 0 to 5% Li₂O, 0 to 8% Na₂O, and 0to 4% K₂O in mass %. The aluminosilicate glass is preferably a glasscontaining 50 to 65% SiO₂, 15 to 25% Al₂O₃, 2 to 5% B₂O₃, 8 to 15% MgO,3 to 7% CaO, 0 to 7% SrO, 0 to 4% BaO, and 0 to 2% Na₂O in mass %. Thealuminoborosilicate glass is preferably a glass containing 50 to 65%SiO₂, 10 to 20% Al₂O₃, 7 to 12% B₂O₃, 0 to 5% MgO, 0 to 7% CaO, 0 to 7%SrO, 0 to 4% BaO, and 0 to 3% Na₂O in mass %.

The luminescent glass article of the present invention includes aluminescent substance composed of one or two or more compounds selectedfrom the group consisting of: MAl₂O₄ or M₄Al₁₄O₂₅ (where M representsCa, Sr, or Ba) containing trace amounts of one or two or more rare earthmetal elements selected from the group consisting of Eu, Ce, Pr, Nd, Sm,Tb, Dy, Ho, Er, Tm, Yb, and Lu; Y₂O₂S containing trace amounts of one ortwo or more rare earth metal elements selected from the group consistingof Eu, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Er, Tm, Yb, and Lu; CaS containing atrace amount of Bi; CaSrS containing a trace amount of Bi; ZnScontaining a trace amount of Cu; and ZnCdS containing a trace amount ofCu. Thus, the luminescent glass article can emit light for a long periodof time, anda luminescence intensity 10 min after the irradiation is 10%or more of the initial luminescence intensity.

The luminescent glass article of the present invention may employ aluminescent substance having an average particle size of 0.1 to 5,000μm, and particularly preferably 50 to 5,000 μm. If the average particlesize is less than 0.1 μm, the surface of the luminescent substancedeteriorates due to heat applied for uniform dispersion of theluminescent substance in the glass, thereby resulting in a reduction ofluminescence intensity. If the average particle size is more than 5,000μm, glass fusion is liable to be inhibited. The average particle size ispreferably 75 to 4,500 μm, and more preferably 100 to 4,000 μm.

In particular, if the average particle size of the luminescent substanceis more than 50 μm, the surface of the luminescent substance maydeteriorate, but inside thereof is not deteriorated. Thus, the ratio ofthe luminescent substance to be deteriorated is reduced, and the numberof particles is smaller than that in a case where the average particlesize is small, to thereby easily provide light transmittance and highluminescence intensity.

The luminescent glass article of the present invention exhibits thecolor of a luminescent substance itself in a bright place, and exhibitsthe color of the glass article due to its light transmission when it isirradiated with light from a back surface. Meanwhile, the luminescentglass article exhibits a luminescent color in a dark place specific tothe luminescent substance itself. The luminescent glass article hasthree different appearances according to brightness and thus can beappropriately designed.

The luminescent glass article of the present invention preferably has100 or less bubbles per 1 cm³. If the luminescent glass article has morethan 100 bubbles, light is scattered by bubbles and the light barelyreaches the luminescent substance. Thus, luminescence intensity ishardly enhanced, and its mechanical strength is liable to be weak. Aswell, the bubbles refer to those each having a diameter of 0.01 mm ormore.

The luminescent glass article of the present invention can be formedinto a block or plate having a thickness of 5 to 100 mm. If theluminescent glass article has a thickness of less than 5 mm, an amountof the luminescent substance present per unit area is small, and thussufficient luminescence intensity is difficult to obtain. If theluminescent glass article has a thickness of more than 100 mm, internalstrain increases, and mechanical strength is liable to be weak. Thethickness of the luminescent glass article is increased to raise theamount of the luminescent substance present per unit area of a designarea, and thus the luminescence intensity is liable to increase. Asdescribed above, the glass article of the present invention formed intoa plate has high mechanical strength and light transmission, and thuscan be used as a part of the lighting design.

The luminescent glass article of the present invention includes theluminescent substance uniformly dispersed in glass. Thus, even if theluminescent glass article is cut, the cut surface has the sameappearance as those of other surfaces. Thus, the luminescent glassarticle can be subjected to cutting or engraving.

Next, a description of the method of manufacturing the luminescent glassarticle of the present invention will be given.

First, a plurality of glass particles, the luminescent substance, and asrequired, an adhesive and/or colorant are added and mixed uniformly. Themixture is poured into a refractory vessel having alumina powder and/orceramic fiber sheet formed on an inner surface thereof. Then, the wholeis subjected to heat treatment between 800 and 1,200° C. for 1 to 10hours, to thereby manufacture the luminescent glass article.

The glass particles have an average particle size of 0.1 to 50 mm,preferably 0.3 to 30 mm, and more preferably 0.5 to 10 mm. If theaverage particle size is more than 50 mm, the glass article is liable toinclude large bubbles and thereby weaken the mechanical strength. If theaverage particle size is less than 0.1 mm, a manufacturing costincreases and the number of bubbles per 1 cm³ is liable to exceed 100.The glass particles in the form of sheets, rod, or beads may be used.

Glass particles obtained by grinding a block of glass or ceramicscontaining a luminescent substance may be mixed with particles of glassor ceramics without a luminescent substance.

The refractory vessel is preferably formed of a material which does notsoften or deform even at 1,200° C. Examples of such a material that canbe used include mullite, cordierite, and alumina ceramic. A ceramicfiber sheet or powder containing as a main component silica, alumina, orzirconia is provided or applied as a release agent onto an inner surfaceof the refractory vessel.

The heat treatment is preferably performed in an inert atmosphere suchas nitrogen gas or argon gas because the luminescent substance isdifficult to oxidize and the luminescence intensity hardly degrades.

EXAMPLES

Hereinafter, the present invention will be described in detail based onexamples.

Table 1 shows luminescent glass articles of the present invention(Examples 1 to 6), and Table 2 shows luminescent glass articles of thepresent invention (Examples 7 to 10) and comparative examples of aluminescent glass article is shown. TABLE 1 Example 1 Example 2 Example3 Example 4 Example 5 Example 6 Glass softening point (° C.) 720 740 720740 740 740 Treatment temperature (° C.) 850 900 850 900 900 900 Contentof luminescent substance (mass %) 2.5 2.5 2.5 2.5 2.5 2.5 Fluidity ∘ ∘ ∘∘ ∘ ∘ Light transmittance (%) 21 25 22 25 48 50 Luminescent color BlueBlue Orange Orange Blue Blue green green green green Initialluminescence intensity (mcd/m²) 320 300 250 220 450 440 Luminescenceintensity 10 76 67 38 27 109 97 min after irradiation (mcd/m²)Luminescence intensity ratio (%) 24 22 15 12 24 22 Visual observation ∘∘ ∘ ∘ ∘ ∘ Mechanical strength (MPa) 25 30 25 30 28 30 Chemical Acidresistance 0.7 0.5 0.8 0.6 0.6 0.5 resistance (mg/cm²) Alkali resistance1.1 0.9 1.2 0.9 1.0 0.9

TABLE 2 Comparative Example 7 Example 8 Example 9 Example 10 ExampleGlass softening point (° C.) 740 740 740 740 720 Treatment temperature(° C.) 900 900 900 900 850 Content of luminescent substance (mass %) 2.52.5 2.5 2.5 20 Fluidity ∘ ∘ ∘ ∘ x Light transmittance (%) 51 50 52 50 5Luminescent color Yellow Yellow Blue Blue Blue green green green greengreen Initial luminescence intensity (mcd/m²) 435 445 420 350 450Luminescence intensity 10 min 89 90 90 67 99 after irradiation (mcd/m²)Luminescence intensity ratio (%) 20 20 21 19 22 Visual observation ∘ ∘ ∘∘ ∘ Mechanical strength (MPa) 27 30 27 30 15 Chemical Acid resistance0.7 0.6 0.5 0.6 0.7 resistance (mg/cm²) Alkali resistance 1.1 0.9 0.91.0 1.3

Example 1

Soda-lime glass having a composition of 70.0% SiO₂, 2.0% Al₂O₃, 4.0%B₂O₃, 2.0% MgO, 7.0% CaO, 14.0% Na₂O, and 1.0% K₂O in mass % was groundinto a size of 0.5 to 2 mm and classified, to thereby prepare glassparticles (A) having an average particle size of 0.6 mm.

Next, 21 g of a luminescent substance containing small amounts of Eu²⁺and Dy³⁺ in Sr₄Al₁₄O₂₅ (ULTRA GLOW NP-2820, average particle size of 20μm, available from Nichia Corporation), and 9 g of anacryl/alkylstyrene-based organic binder as an adhesive were added to 813g of the glass particles (A). The mixture was stirred for 30 min, filledinto a refractory ceramic vessel, and subjected to heat treatment in anitrogen atmosphere at 850° C. for 3 hours, to thereby manufacture aluminescent glass article of 196×96×18 mm.

The refractory ceramic vessel had an inner size of 200×100×150 mm andwas formed of cordierite. Alumina powder was applied onto an innersurface of the vessel, and a ceramic fiber sheet having a composition of95 mass % silica and 5 mass % alumina was placed on a base of thevessel.

Example 2

Borosilicate glass having a composition of 70.2% SiO₂, 5.4% Al₂O₃, 13.5%B₂O₃, 0.5% CaO, 6.7% Na₂O, and 2.2% K₂O in mass % was ground into a sizeof 0.5 to 2 mm and classified, to thereby prepare glass particles (B)having an average particle size of 0.6 mm.

Then, a luminescent glass article was manufactured in the same manner asin Example 1 except that: 779 g of the glass particles (B), 20 g of aluminescent substance (ULTRA GLOW NP-2820, average particle size of 20μm, available from Nichia Corporation), and 8 g of anacryl/alkylstyrene-based organic binder were used; and the mixture wassubjected to heat treatment at 900° C.

Example 3

A luminescent glass article was manufactured in the same manner as inExample 1 except that 21 g of a luminescent substance containing smallamounts of Eu²⁺, Dy³⁺, Ti⁴⁺, and Mg²⁺ in Y₂O₂S (ULTRA GLOW NP-2850,average particle size of 30 μm, available from Nichia Corporation) wasused.

Example 4

A luminescent glass article was manufactured in the same manner as inExample 2 except that 20 g of a luminescent substance containing smallamounts of Eu²⁺, Dy³⁺, Ti⁴⁺, and Mg²⁺ in Y₂O₂S (ULTRA GLOW NP-2850,average particle size of 30 μm, available from Nichia Corporation) wasused.

Example 5

A luminescent glass article was manufactured in the same manner as inExample 2 except that: 20 g of a luminescent substance containing smallamounts of Eu²⁺ and Dy³⁺ in SrAl₂O₄ (α-FLASH PB500, average particlesize of 500 μm, available from LTI Corporation) was used; and themixture was subjected to heat treatment in atmospheric air.

Example 6

A luminescent substance of 67 g containing small amounts of Eu²⁺ andDy³⁺ in SrAl₂O₄ (α-FLASH PB500, average particle size of 500 μm,available from LTI Corporation) and 27 g of an acryl/alkylstyrene-basedorganic binder were added to 2,608 g of the glass particles (B). Themixture was stirred for 30 min, poured into a refractory ceramic vessel,and subjected to heat treatment in atmospheric air at 900° C. for 3hours, to thereby manufacture a luminescent glass article of 196×96×60mm.

Example 7

A luminescent glass article was manufactured in the same manner as inExample 5 except that 20 g of a luminescent substance containing smallamounts of Eu²⁺ and Dy³⁺ in SrAl₂O₄ (α-FLASH PB500, average particlesize of 500 μm, available from LTI Corporation) was used.

Example 8

A luminescent glass article was manufactured in the same manner as inExample 6 except that 67 g of a luminescent substance containing smallamounts of Eu²⁺ and Dy³⁺ in SrAl₂O₄ (α-FLASH PB500, average particlesize of 500 μm, available from LTI Corporation) was used.

Example 9

Borosilicate glass having a composition of 70.2% SiO₂, 5.4% Al₂O₃, 13.5%B₂O₃, 0.5% CaO, 6.7% Na₂O, and 2.2% K₂O in mass % was ground into a sizeof 2 to 5 mm and classified by particle, to thereby prepare glassparticles (C) having an average particle size of 3.0 mm.

Next, 56 g of a luminescent substance containing small amounts of Eu²⁺and Dy³⁺ in SrAl₂O₄ (α-FLASH PB500, average particle size of 500 μm,available from LTI Corporation) and 22 g of an acryl/alkylstyrene-basedorganic binder were added to 2,189 g of the glass particles (C). Themixture was subjected to heat treatment in atmospheric air at 900° C.for 3 hours, to thereby manufacture a luminescent glass article of196×96×50 mm.

Example 10

A luminescent glass article was manufactured in the same manner as inExample 9 except that a luminescent substance containing trace amountsof Eu²⁺ and Dy³⁺ in SrAl₂O₄ (LumiNova BGL, average particle size of 500μm, available from Nemoto & Co., Ltd.) was used.

Comparative Example

A luminescent glass article was manufactured in the same manner as inExample 1 except that 203 g of a luminescent substance containing smallamounts of Eu²⁺ and Dy³⁺ in Sr₄Al₁₄O₂₅ (ULTRA GLOW NP-2820, averageparticle size of 20 μm, available from Nichia Corporation) was used.

A glass softening point was measured by using a macro-type differentialthermal analyzer (manufactured by Rigaku Corporation), and a temperatureof the obtained fourth inflection point was regarded as the softeningpoint.

Fluidity was determined through visual observation of a sample surfaceafter heat treatment. A sample having a smooth and glossy surface wasrepresented by “o”, and a sample having a rough and dull surface wasrepresented by “×”. A luminescent color was determined through visualobservation in a dark place.

A light transmittance refers to a value obtained by: cutting aluminescent glass article into a size of 50×50×10 mm; subjecting bothsurfaces of the cut-out piece to optical polishing to prepare a platesample; adjusting light directly illuminated from a light source of afluorescent lamp to an illuminance meter (LX-1334, manufactured byCustom K.K.) at an illuminance of 1,000 lux; measuring an illuminance(lux) 10 times with the sample placed between the fluorescent lamp andthe illuminance meter; and dividing an average value thereof by 1,000lux and multiplying the quotient by 100.

The luminescent color was determined through visual observation in adark place.

The luminescence intensity was determined by: cutting a luminescentglass article into a size of 50×50×10 mm; subjecting both surfaces ofthe cut-out piece to optical polishing to prepare a plate sample;leaving the sample standing in a dark place for 8 hours; irradiatinglight of 1,000 lux for 20 min; measuring an luminescence at 10 positionseach just after the irradiation or 10 min after the irradiation by usinga illuminance meter (LS-100, manufactured by Konica Minolta Holdings,Inc.); and obtaining the respective average values.

Visual observation was performed by: cutting a luminescent glass articleinto a size of 50×50×10 mm; subjecting both surfaces of the cut-outpiece to optical polishing to prepare a plate sample; leaving the samplestanding in a dark place for 8 hours; irradiating light of 1,000 lux for20 min; and visually observing the sample 1 hour after the irradiation,to thereby determine whether the sample emitted light or not.

Mechanical strength was measured by: cutting a sample into a size of10×70×8 (mm); and performing a three-point bending test by using abending tester (EZTest-500N, manufactured by Shimadzu Corporation) at adistance between supports of 30 mm and a crosshead speed of 0.5 mm/min.

Chemical resistance was evaluated by determining acid resistance andalkali resistance. The chemical resistance was determined by: cutting asample into a size of 25×25×5 (mm); subjecting the sample surface tomirror polishing; measuring a reduced amount of mass of the sampleimmersed in a 1% sulfuric acid solution for acid resistance or a 1%sodium hydroxide solution for alkali resistance at 90° C. for 24 hours;and calculating the reduced amount per surface area.

Luminescent glass articles of Examples 1 to 10 each had a lighttransmittance of 20% or more, an initial luminescence intensity of 200mcd/mm² or more, and an luminescence intensity 10 min after theirradiation of 12% or more of the initial luminescence intensity. Theluminescent glass articles each had a luminescence intensity that can besufficiently confirmed through visual observation. In particular, theluminescent glass articles of Examples 5 to 10 each had a lighttransmittance of 48% or more, an initial luminescence intensity of 350mcd/mm² or more, and an luminescence intensity 10 min after theirradiation of 19% or more of the initial luminescence intensity.

Luminescent glass articles of Examples 1 to 10 all had good fluidity,high mechanical strength of 25 MPa or more, and chemical resistanceincluding acid resistance of 0.8 mg/cm² or less and alkali resistance of1.2 mg/cm² or less.

Meanwhile, the luminescent glass article of the Comparative Example hadpoor fluidity and a low mechanical strength of 15 MPa. Although theluminescent glass article of the Comparative Example had a largercontent of the luminescent substance than those of the luminescent glassarticles of Examples 5 to 10, the luminescent glass article of theComparative Example had initial luminescence intensity. The luminescenceintensity 10 minutes after the irradiation was comparable to those ofthe luminescent glass articles of Examples 5 to 10.

INDUSTRIAL APPLICABILITY

As described above, the luminescent glass article of the presentinvention has high mechanical strength, can provide sufficientluminescence intensity, and can be manufactured at low cost. Further,the luminescent glass article itself emits light without turning onillumination, to thereby allow easy recognition of a wall or step andprevention of an accident, such as collision or falling. Therefore, theluminescent glass article of the present invention is suitable forpavements, building covering materials building interior materials, artobjects, guide lights, sidewalk lights, foot lights, window members, andthe like.

1. A luminescent glass article, characterized by comprising aluminescent substance dispersed uniformly in glass, wherein: lighttransmittance is 20 to 90% at a thickness of 10 mm; and an initialluminescence intensity just after irradiation of light of 1,000 lux for20 min is 200 to 4,000 mcd/m².
 2. A luminescent glass article accordingto claim 1, characterized in that a luminescence intensity 10 min afterthe irradiation, is 10% or more of the initial luminescence intensity.3. A luminescent glass article according to claim 1, characterized inthat a content of the luminescent substance, is 0.1 to 5 mass %.
 4. Aluminescent glass article, characterized by comprising a luminescentsubstance dispersed uniformly in glass, wherein the content of theluminescent substance is 0.1 to 5 mass %.
 5. A luminescent glassarticle, according to claim 4, characterized in that the glass, has asoftening point of 650 to 1,100° C.
 6. A luminescent glass articleaccording to claim 5, characterized in that the glass, is composed ofone type or two or more types of glass selected from the groupconsisting of soda-lime glass, borosilicate glass, aluminosilicateglass, and aluminoborosilicate glass.
 7. A luminescent glass articleaccording to claim 4, characterized in that the luminescent substance,has an average particle size of 50 to 5,000 μm.
 8. A luminescent glassarticle according to claim 4, characterized in that the luminescentglass article, is formed into a block or plate having a thickness of 5to 100 mm.
 9. A method of manufacturing a luminescent glass article,characterized by comprising: mixing a plurality of glass particles and aluminescent substance; pouring the mixture into a refractory vessel; andsubjecting the mixture to heat treatment for sintering.
 10. Aluminescent glass article, according to claim 1, characterized in thatthe glass, has a softening point of 650 to 1,100° C.
 11. A luminescentglass article according to claim 10, characterized in that the glass, iscomposed of one type or two or more types of glass selected from thegroup consisting of soda-lime glass, borosilicate glass, aluminosilicateglass, and aluminoborosilicate glass.